Abstract
Cabozantinib (CBZ) N-(4-((6,7-dimethoxyquinolin-4-yl) oxy) phenyl)-N-(4-fluorophenyl) cyclopropane-1,1-dicarboxamide) (XL184), an inhibitor of MET and vascular endothelial growth factor receptor (VEGFR-2), is an agent approved for the treatment of several types of carcinoma such as medullary thyroid and renal. Recent studies are encouraging for the effectiveness of CBZ in the treatment of osteosarcoma. Because of the complex nature of the microenvironment of osteosarcoma cell sites, in order to better understand the direct effects of CBZ on osteosarcoma cells, in vitro studies were conducted with the human osteosarcoma cell line, G292. Experiments were focused on the effects of CBZ on cell metabolic activity, differentiation, and apoptosis as well as the modulation of responses to growth factors such as platelet-derived growth factor (PDGF) and insulin like growth factor (IGF-I). The results indicate that CBZ can increase the activity of caspase 3/7 as an indicator of apoptosis as well as decrease cellular activity, measured by MTT assay and differentiation assessed by alkaline phosphatase activity. The drug partially downregulated the effects of PDGF on MTT activity and had significant inhibitory effects on the G292 cells response to IGF-I and production of VEGF.
This study presents original information on responses of G292 human osteosarcoma cells to the chemotherapy agent, CBZ, and provides in vitro data consistent with the potential therapeutic effects of this agent for osteosarcoma.